Evaporative coolers
When the humidity is low, evaporative coolers can be a cost-effective way to cool your home.
Here are answers to some frequently asked questions about these economical appliances. Please select a category from the list at the left.
Q: Our home has single-pane windows, a heat pump, an evaporative cooler and ceiling fans throughout.
It also has nine mature pine trees lining the south and west yards. We are home all day, every day. What is the
most efficient way to cool our home?
A: The most efficient way to cool your home is not always the most comfortable way,
but I'll respond to your question by taking both comfort and efficiency into account.
During the fall and spring, you can probably close all the windows and doors in the house during the day,
including shading devices, and get by with just running the ceiling fans. As night approaches and the
outside temperature falls, open up the house and continue to use the fans to help pull the cool outside air inside.
As summer nears and the outside temperature rises, you'll want to begin running your evaporative cooler.
To reduce the amount of energy used by your cooler, make sure that it is thermostatically controlled.
You can still run your ceiling fans to help circulate the air inside your house.
In mid-July when the monsoons approach, you'll find that your evaporative cooler is no longer capable of
keeping you comfortable, so it's time to switch over to your heat pump. When you make the switch, be
sure to insert the baffle plate, which looks like a flat cookie sheet, in the cooler so that you can isolate
the cooler. If you don't, you'll draw hot outside air in through your evaporative cooler when the heat
pump is operating. Make sure that all evaporative cooler vents are closed and sealed when you switch
to the heat pump.
As the monsoons end and humidity drops, you can switch back to your evaporative cooler. Be sure to
reopen the vents and remove the baffle plate. Try not to switch back and forth between the heat pump
and the evaporative cooler, as it causes both units to run inefficiently.
Q: Is it cheaper to operate a 220-volt swamp cooler than a 110-volt swamp cooler?
A: Typically, motors that are supplied with higher voltages will consume slightly less energy
than those supplied at lower levels. To show this, you can use the formula for calculating the wattage of an
electrical appliance: amps x volts = watts.
For example, a 3/4 horsepower evaporative cooler motor supplied with 115 volts will draw 11 amps, whereas
the same motor supplied with 230 volts will draw 5.4 amps (these are actual specifications taken directly from
a motor catalog). Doing the match, you end up with 115 x 11 = 1,265 watts compared to 230 x 5.4 = 1,242 watts.
When you increase the voltage to an appliance, you reduce the amperage. Likewise, when you decrease the
voltage, you increase the amperage.
If the cooler runs for 12 hours a day, the 115-volt motor will consume 455 kWh (1,265 x 12 x 30 divided by 1,000)
while the 230-volt motor will consume 447 kWh. So the 230-volt motor will cost less per month to operate,
although the 230-volt motor may cost more to purchase.
Q: I have a mobile home with an evaporative cooler and a window air conditioner. If I turn off the
water and just use the blower on the evaporative cooler, will that help or hinder the operation of my air
conditioner?
A: Running your evaporative cooler will negate the cooling benefits of your window
air conditioner. The air distributed by your evaporative cooler comes directly from outside. So if it's
105 degrees outside, your evaporative cooler will distribute 105-degree air to your home.
A window air conditioner on the other hand, recirculates the air within your home over a cold coil and
distributes this cold air into the room. Combining hot evaporative-cooling air with cold air-conditioning
air will give you warm, uncomfortable air.
The bottom line is, when it's humid outside, just run your window air conditioner. When the outdoor
humidity drops after the monsoon season, turn the air conditioner off and run your evaporative cooler
with the water turned on.